Why use baking soda around tomato plants?
Written by
Benjamin Miller
Reviewed by
Prof. Martin Thorne, Ph.D.Gardeners use baking soda around tomato plants essentially to temporarily raise soil pH, which positively affects calcium availability. The alkaline properties help neutralize acidic soil conditions that sequester calcium from plants. I use it as a quick pH adjuster at critical stages of fruit development.
pH Adjustment
- Sodium bicarbonate temporarily raises pH by neutralizing acidic compounds
- Effect lasts 2-3 weeks requiring repeated applications during peak growth
- Overuse causes sodium buildup damaging soil structure and root health
Calcium Interaction
- Higher pH unlocks insoluble calcium compounds making them plant-available
- Does not add calcium merely improves access to existing reserves
- Requires existing soil calcium levels above minimum thresholds
Microbial Impact
- Altered pH shifts microbial populations affecting nutrient cycling
- Temporarily suppresses fungal diseases like powdery mildew on leaves
- Repeated use reduces beneficial mycorrhizal fungi colonies
For optimal results, baking soda and base solutions should be used together. First, ensure uniform irrigation with drip irrigation, as calcium will only move with water. It's essential to test your soil pH before applying baking soda. I use this only at pH levels below 6.0 during the fruiting season.
Apply properly to avoid damage. Baking soda must be fully dissolved in water before it is applied to the soil. Do not sprinkle powdered baking soda directly on plants or the soil surface. I water the plants first and then use a second layer to the moist soil to minimize root shock.
After treatment, closely observe the plants. Monitor new shoots for growth vigor and fruit for blemish-free performance. If new growth shows no progress after two weeks, consider a permanent solution to the pH imbalance, such as lime. Baking soda will provide a temporary solution to the pH imbalance, but not a permanent one.
Balance with organic matter. Compost buffers pH naturally and improves soil structure. I incorporate compost pre-planting and will use baking soda as an emergency measure when excessive rainfall threatens the soil's acidity. This mixture holds a steady pH.
Read the full article: Tomato Blossom End Rot Explained Simply
